The present invention relates to video graphics for computer-generated displays and specifically is disclosed in relation to displays for training simulators as well as entertainment with wide fields of view.
Over the past few decades, a quest has continued for realistic computer graphics presentations. One objective has been to provide realistic computer-generated images for simulation systems. That is, the need has existed for images of sufficient realism that an observer perceives the displays as real objects rather than representations of simulation data from a computer memory. In addition to realism, simulation display systems must be capable of providing dynamic or moving images. For example, a flight simulator depicts views as observed from the cockpit of a moving airplane.
One technique for providing simulator displays involves a relatively large viewing screen encompassing the viewer. That is, a color video display is developed on a spherical viewing screen mounted to dominate the view from a platform carrying a simulated aircraft cockpit. Traditionally, such displays have been formed by combining separate, but spatially identical, red, green, and blue image components. Accordingly, by controlling the relative intensities of the three colors, a full color spectrum is perceived in the combined or composite image.
In the past, to develop wide field of view simulator displays, three separate video projectors have been employed to provide the three color images that are combined on a spherical viewing screen. For realism, the display must be characterized by a wide field of view and high resolution. However, inherently, video-generated wide fields of view have low resolution. As a result, it has been previously proposed to inset a high resolution image in the wide field at the area of interest. Specifically, a section of the background wide field image is removed or blanked from an inset area coinciding to the area of interest. That area is then replaced with a small field of view, high resolution image provided by another projection system. Traditionally, the inset image has required three projection sources (one for each color component) for a full color image. Consequently, considerable cost and technical difficulty is involved in providing and synchronizing the numerous, (e.g. six) projection sources for effective and convenient operation within the confines of a simulator.
In general, the present invention comprises a simplified and economical system to achieve a full color, detailed at the area of display interest. The present invention is based on recognizing the inability of the human eye to distinguish color at high spatial frequencies (small detail). Essentially, only one color, e.g. green, is blanked from the wide view display at the area of interest. A high resolution inset of the single deleted color then is projected in the inset area. Note that the human eye is most sensitive to the color green with the consequence of favoring the modification in that color. Essentially, the relatively large, wide fields of view, image components, e.g. red, blue and green, are projected as the background. A wide field background image in the third color, e.g. green, also is projected; however, with the inset area blanked. Thus, three projectors may be employed for the wide field background. A fourth projector provides the single detailed color (green) of the inset.
In demonstrations of the system involving a variety of images, observers were unable to perceive differences between the inset area and the background until resolution differences approached a ratio of ten to one. Below such a ratio, no abnormalities were reported as noticeable. Accordingly, the invention affords a considerably simplified system with resulting convenience and economy.